Table 3. Simple and multiple mixed model analyses in teeth with a vertical height of the alveolar bone <10 mm.

Variables		Simple mixed model			Multiple mixed model
		B estimate	Confidence interval	P value	B estimate	Confidence interval	P value
Sex
	Male (ref.)	0	-	-	0	-	-
	Female	−0.77	−2.25, 0.7	0.2904	−0.64	−2.02, 0.74	0.3372
Age		−0.04	−0.03, 0.1	0.3427	0	−0.07, 0.06	0.8795
Number of extracted teeth
	Single extraction (ref.)	0	-	-	0	-	-
	Multiple extraction	1.26	−0.21, 2.73	0.0898	1.09	−0.29, 2.48	0.1137
Tooth site
	First premolar (ref.)	0	-	-	0	-	-
	Second premolar	−1.23	−3.44, 0.99	0.2621	−1.63	−3.73, 0.47	0.1184
	First molar	−1.49	−3.59, 0.62	0.1567	−1.24	−3.6, 1.12	0.2799
	Second molar	−2.31	−4.73, 0.11	0.0600	−2.98	−5.37, −0.59	0.0181
Reason for extraction
	Periodontal (ref.)	0	-	-	0	-	-
	Endodontic	−1.13	−3.97, 1.7	0.4168	−0.29	−2.95, 2.37	0.8184
	Fracture	0.35	−2.11, 2.8	0.7734	0.28	−2.02, 2.58	0.7974
	Unknown	2.11	−1.12, 5.34	0.1893	4.26	1.27, 7.25	0.0084
Time interval following tooth extraction
	≤6 months (ref.)	0	-	-	0	-	-
	>6 and ≤12 months	1.28	−0.41, 2.97	0.1310	0.9	−0.64, 2.43	0.2328
	>12 months	0.01	−1.85, 1.87	0.9898	−0.54	−2.12, 1.13	0.5006
Relationship between the root and the sinus floor
	Class I (ref.)	0	-	-	0	-	-
	Class II	−0.13	−1.71, 1.45	0.8633	−1.25	−2.86, 0.36	0.1196
	Class III	0.29	−1.59, 2.17	0.7528	−0.94	−2.78, 0.89	0.2911
	Class IV	−0.56	−3.02, 1.9	0.6403	−1.51	−3.95, 0.92	0.2054
	Class V	−0.4	−2.76, 1.96	0.7268	−1.91	−4.36, 0.54	0.1169
Sinus mucosal thickening
	≤5 mm (ref.)	0	-	-	0	-	-
	>5 and ≤10 mm	−0.79	−2.58, 1.00	0.3719	−0.55	−2.22, 1.12	0.4903
	>10 mm	−1.73	−4.52, 1.07	0.2146	−1.81	−4.31, 0.06	0.8795